Passive Transport

Does not expend cellular energy for the movement to take place Ex-rolling down a hill

Parts of a Solution Solute: what gets dissolved Solvent: What does the dissolving, more plentiful that solute Solution: the mixture of solutes and solvent Example: H 2 O and NaCl Solute: NaCl Solvent: H 2 O Solution: H 2 O and NaCl

3 types of Passive Transport: 1.Diffusion 2.Osmosis 3.Facilitated Diffusion

Diffusion Passive Transport WITHOUT a Membrane

I. DIFFUSION: Definition: Transport of molecules (of solutes and solvents) From an area of higher concentration to an area of lower concentration Until equal distribution of concentrations reached in all areas (EQUILIBRIUM) Due to the random movement of molecules

Conceptual Diagram:

Review of the Types of Membranes: 1.Permeable 2.Impermeable 3.Semi-permeable

1. Permeable ALL types of molecules can get through, regardless of size or charge.

2.Impermeable (non-permeable) NO molecules can get through

3. SEMI-PERMEABLE !!! : SOME MOLECULES CAN GET THROUGH Very small or Non-charged

Diffusion: Without a Membrane Osmosis: With a Membrane

Osmosis and Facilitated Diffusion Passive Transport WITH a Membrane

II.OSMOSIS: Definition: Diffusion through a membrane: Movement of H 2 O from to high to low concentration THROUGH A MEMBRANE until equilibrium

II.OSMOSIS:

How do you get different concentrations of water (2 ways)? 1.Change the amount of solute or solvent. 2.Add a membrane

3 Types of Solutions (outside of cell): 1.Hypertonic 2.Hypotonic 3.Isotonic

1.Hypertonic: MORE More solute, less solvent (H 2 O) outside of the cell 90% water 80% water

2. Hypotonic: LESS Less solute, more solvent outside of the cell.

3. Isotonic: EQUAL Equal amounts of solute/solvent concentrations on both sides of membrane

Consequences: Hypertonic  Cell Shrinking In a plant cell: PLASMOLYSIS In an animal cell: CRENATION (Shriveled) Examples: Drinking out of ocean when you are dying of thirst or  Placing a fresh water fish or plant in salt water…  Plant Wilting sue to lack of water 

Hypotonic  In a plant cell: TURGID (Firm) In an animal cell: CYTOLYSIS (Lysed: Cell Bursting) Examples: Place a salt water fish in fresh water  Red Blood Cells in pure water Plants standing tall after being watered

Osmotic Pressure = Turgor Pressure As a result of osmosis, extra water molecules accumulate on one side of membrane and cause pressure on the membrane  “Turgor” Example: water

III. FACILITATED DIFFUSION: Protein Channels in the cell membrane accept only specific molecules, like a lock accepts a particular key.

III. FACILITATED DIFFUSION:

Many of these protein channels are “two-way” and are called PORES. These transport ions or molecules (solutes) through membranes in either direction

III. FACILITATED DIFFUSION: Like an open door allows you to pass into or out of a room. Different solute molecules fit different pores This depends on Size Polarity Shape of molecule Eg. Glucose

III. FACILITATED DIFFUSION: When a solute that is plentiful on one side of membrane, they will pass by diffusion toward other side with the lower concentration. Until concentration becomes equal on both sides

DON’T FORGET, THESE WERE ALL PASSIVE TRANSPORT – SO THE CELL DID NOT NEED TO EXPEND ANY NRG TO MAKE IT HAPPEN!!!!!